This invention relates generally to a quartz crystal wristwatch for timekeeping and more particularly to a quartz crystal wristwatch where temperature compensation is provided by modifying the output signals which are outputted from the divider network receiving the high frequency signal from the quartz crystal oscillator circuit. The quartz crystal wristwatch of this invention has a controlling device for reading the contents of a memory means where data indicating the required magnitude of frequency correction is stored, and for generating a compensation signal corresponding to the contents of the memory means. The amount of compensation which is required is calculated from the predicted temperature of the wristwatch when it is worn.
In the prior art, in a conventional method of temperature compensation for a quartz crystal wristwatch, the temperature-compensated output of the oscillator is obtained by adding a temperature sensitive element to the quartz crystal oscillator. One condenser having a capacity-temperature characteristic is generally used as the temperature sensitive element. Timekeeping accuracy can be obtained to some degree by this prior art method. The timekeeping accuracy is represented as a monthly rate of plus or minus 10 to plus or minus 20 seconds. It is impossible to achieve a superior timekeeping accuracy by providing only a single variable condenser. So, it is then necessary to add a condenser for controlling the condenser having the temperature-capacity characteristic. In such a situation, adding the condenser limits the space available for other elements for conducting the functions normal to the timepiece, and makes the design for attaining timekeeping accuracy very complicated. Furthermore, manufacturing costs are raised by temperature compensating by means of additional components.
There are many other methods in the prior art for obtaining the temperature compensated output of an oscillator, but these methods when applied have many disadvantages in terms of space requirements, complexity, cost and the like.
What is needed is a quartz crystal wristwatch which is temperature compensated without the need to compensate the oscillator circuit per se by means of additional components. It is also desirable that any temperature compensating device be adaptable to integrated circuit design.